Field of the Invention
The present invention relates to a driving apparatus, more specifically, to a linear driving type of vibration wave motor, called hereinafter linear vibration wave motor.
Description of the Related Art
In a conventional linear vibration wave motor, a high frequency voltage is applied to a piezoelectric element to vibrate a vibrator on which a piezoelectric element is fixed. Vibration of vibrator drives a sliding member pressed by the vibrator. Various attempts have been made to provide a compact type of linear vibration wave motors that are capable of maintaining high power output and enhancing driving efficiency.
For example, in a linear vibration wave motor disclosed in Japanese Patent application Laid-open No. 2009-011099, a vibrator having a piezoelectric element is provided with two drivers abutted to a driven member and four rolling members between the driven member and a base member. And the four rolling members are arranged with spacing so as not to enter between the two driving elements in the driving direction of driven member.
However, it is necessary to make longer the arrangement spacing of four rolling members in the driving direction of the driven member, in order to maintain the configuration that the four rolling members do not enter between the two drivers in the driving direction of the driven member, in the linear vibration wave motor disclosed in Japanese Patent application Laid-open No. 2009-011099. As a result, there has been a problem that a full length of unit in the driving direction becomes large.